【Boost】timer、progress_timer和progress_display

 

 

Table of Contents

• 1 timer
• 2 progress_timer
• 3 progress_display

1 timer

timer t; //声明一个timer类对象t，调用构造函数开始计时
timer t(t0); //调用默认的复制构造函数，t的流逝时间与t0相同
成员函数：

1. elapsed() 流逝的时间
   
2. elapsed_max() 计时器最大范围
   
3. elapsed_min() 计时器最小范围
   
4. restart() 重新开始计时
   

2 progress_timer

该类构造函数开始计时，析构函数则在适当的位置以适当的形式打印自构造函数调用开始到析构函数调用的时间。

3 progress_display

以进度条的形式显示进度：

 

0%   10   20   30   40   50   60   70   80   90   100%
|----|----|----|----|----|----|----|----|----|----|
************************************

progress_display( unsigned long expected_count,
                  std::ostream& os,  // os is hint; implementation may ignore
                  const std::string & s1 = "\n", //leading strings
                  const std::string & s2 = "",
                  const std::string & s3 = "" )

成员函数：

1. count() 进度计数
   
2. expected_count() 返回初始化该类对象的expected_count值
   
3. restart(unsigned long expected_count) 中止当前进度条的显示，并重新赋值
   

   
   

文档中给的例子：

 

//  timer, job_timer, and progress_display sample program  -------------------//

//  Copyright Beman Dawes 1998.  Distributed under the Boost
//  Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//  See http://www.boost.org/libs/timer for documentation.

//  Revision History
//  12 Jan 01  Cut time to 1.0 secs to speed regression tests (Beman Dawes)
//  25 Sep 99  added elapsed_min() and elapsed_max() reporting
//  16 Jul 99  Second beta
//   6 Jul 99  Initial boost version

#include <boost/progress.hpp>
#include <iostream>
#include <climits>

using boost::timer;
using boost::progress_timer;
using boost::progress_display;
using std::cout;
using std::endl;

int main()
{

    timer t0;  // used only for elapsed_max() and elapsed_min()

    cout << "timer::elapsed_min() reports " << t0.elapsed_min() << " seconds\n";
    cout << "timer::elapsed_max() reports " << t0.elapsed_max()
         << " seconds, which is " << t0.elapsed_max()/3600.0 << " hours\n";

    cout << "\nverify progress_display(0) doesn't divide by zero" << endl;
    progress_display zero( 0 );  // verify 0 doesn't divide by zero
    ++zero;

    long loops;
    timer loop_timer;
    const double time = 1.0;

    cout << "\ndetermine " << time << " second iteration count" << endl;
    for ( loops = 0; loops < LONG_MAX
            && loop_timer.elapsed() < time; ++loops ) {}
    cout << loops << " iterations"<< endl;

    long i;
    bool time_waster; // defeat [some] optimizers by storing result here

    progress_timer pt;
    timer t1;
    timer t4;
    timer t5;

    cout << "\nburn about " << time << " seconds" << endl;
    progress_display pd( loops );
    for ( i = loops; i--; ) {
        time_waster = loop_timer.elapsed() < time;
        ++pd;
    }

    timer t2( t1 );
    timer t3;
    t4 = t3;
    t5.restart();

    cout << "\nburn about " << time << " seconds again" << endl;
    pd.restart( loops );
    for ( i = loops; i--; ) {
        time_waster = loop_timer.elapsed() < time;
        ++pd;
    }

    if ( time_waster ) cout << ' ';  // using time_waster quiets compiler warnings
    progress_display pd2( 50, cout, "\nLead string 1 ", "Lead string 2 ", "Lead string 3 " );
    for ( ; pd2.count() < 50; ++pd2 ) {}

    cout << "\nt1 elapsed: " << t1.elapsed() << '\n';
    cout << "t2 elapsed: " << t2.elapsed() << '\n';
    cout << "t3 elapsed: " << t3.elapsed() << '\n';
    cout << "t4 elapsed: " << t4.elapsed() << '\n';
    cout << "t5 elapsed: " << t5.elapsed() << '\n';
    cout << "t1 and t2 should report the same times (very approximately "
         << 2*time << " seconds).\n";
    cout << "t3, t4 and t5 should report about the same times,\n";
    cout << "and these should be about half the t1 and t2 times.\n";
    cout << "The following elapsed time should be slightly greater than t1."
         << endl;
    return 0;
} // main

Author: visaya fan <visayafan[AT]gmail.com>

Date: 2012-04-30 00:22:18

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